Green Fire Retardants for Structural Timber

Timber-frame fires and the need for retardants

In 1986, UK building regulations which had restricted the construction of multi-storey timber-framed buildings since Christopher Wren’s redesigning of London after the Great Fire in 1666 were relaxed. A whole new field opened up for the construction industry and timber buildings began popping up around the country.

A cultural shift towards a greener world helped encourage the use of structural timber, whose lightweight frames also reduced the need for large transport emissions and deep, complex foundations. The government’s house building initiative speculated that one in four new dwellings should be timber framed (3), fuelling the growth of the industry.

The construction of timber-framed structures has not, however, been without its problems. Whilst the completed structures show no more susceptibility to large fires than traditional building methods (4) due to the significant fire regulations which apply, incomplete structures appear to be particularly vulnerable to rapid fire growth. The graph below (Fire Monitor 2009-2010, 4) illustrates the hazard posed by incomplete timber structures.

Indeed, a spate of high-profile fires recently (including multi-storey flats in Peckham, Glasgow, Basingstoke, and Colindale) has prompted criticism from the Chief Fire Officers Association. The Health and Safety Executive, in response to the fires, has released a report Fire safety in construction which gives specific regard to timber-frame construction. It is specifically noted in Section 182 that "some timber frame structures are vulnerable to rapid fire spread and possible collapse in the early stages of construction as the timber is not protected" (6).

These fires have illustrated that the use of unprotected structural timber in construction poses a considerable risk to property and lives. In the Colindale incident, the entire structure collapsed after around 10 minutes (5). It is clear that a vulnerable material such as timber requires fire protection early on in its use, not just as an end-product.

This project aims to investigate the benefits that fire retardants could provide for structural timber, and how these can be incorporated whilst maintaining timber’s status as a “green” construction material.

Fire Statistics Monitor

Chart 8 from Fire Statistics Monitor (4) clearly shows that large fires are more common for timber frame buildings under construction than for traditional building methods. The same report shows that timber-frame buildings are no more susceptible to fire than "No special construction" techniques once complete (Charts 6 and 7).

The report notes that there are too few casualties to draw any conclusion about a difference in casualty rate between buildings of timber construction and buildings of "no special construction".

Better a thousand times careful than once dead ~ Proverb